Synthflow AI

Best for: Regulated or enterprise workloads - compliance attestations and an enterprise plan; AI agents and automation - an agent-ready surface (MCP / llms.txt); Teams needing broad API coverage out of the box

Avoid if: You want to try it free before paying

Pricing model

Usage-based [2]docs.synthflow.ai/billing“Pay As You Go — Starting price: "$0/month" — Per-minute rate: "LLM + voice engine (~$0.15–0.24/min)" — Concurrency: 5 units (expandable)”docs.synthflow.ai/pay-as-you-go“Combined, effective rates typically fall between $0.15–0.24 per minute”

Published pricing

✓ Yes [3]docs.synthflow.ai/pay-as-you-go“Combined, effective rates typically fall between $0.15–0.24 per minute”docs.synthflow.ai/billing“Pay As You Go — Starting price: "$0/month" — Per-minute rate: "LLM + voice engine (~$0.15–0.24/min)"”

Free tier

✗ No [4]docs.synthflow.ai/pay-as-you-go“No payment method required for platform exploration... but usage-based charges begin once you add a payment method and start making calls or using chat.”

Self-serve signup

✓ Yes [5]docs.synthflow.ai/pay-as-you-go“No payment method required for platform exploration (agent creation, flow design, knowledge bases, voice previews). Payment method mandatory to make calls or use chat agents.”

Requires sales call

✗ No [6]docs.synthflow.ai/billing“Pay As You Go — Starting price: "$0/month" — Target use case: Builders, pilots, and small-scale deployments”

Enterprise plan

✓ Yes [7]synthflow.ai/pricing“Enterprise contracts start at $30,000 annually. Final pricing is scoped around call volume, concurrency, telephony setup, integrations, security needs, and launch support.”

• Built-in telephony
• Outbound calling
• BYO models

Supported actions

inbound_telephony, outbound_telephony, sip_trunking, call_transfer, warm_transfer, function_calling, tool_calling, interruption_handling, knowledge_base, call_recording, voicemail_detection, sentiment_analysis, human_handoff, sms_followup, realtime_conversation, multi_agent_orchestration, batch_calling, call_analytics, auto_qa, web_widget, websocket_streaming, byo_llm, byo_voice [8]synthflow.ai/integrations“Connect your own OpenAI key to power your assistants”docs.synthflow.ai/llms-full.txt“Warm Transfers: Seamlessly transfer calls from your AI agent to human agents or external phone systems; Transfer Types: TEL (phone numbers), SIP endpoints, and dynamic routing supported”

Regions

United States, European Union, United Kingdom, Canada, Latin America [9]docs.synthflow.ai/reference/getting-started-with-your-api“The platform supports three regional deployments (Global, US, EU) with corresponding base URLs.”

Languages

English (American), English (British), English (Australian), Spanish, French, German, Italian, Portuguese (Brazilian), Portuguese (European), Dutch, Polish, Swedish, Norwegian, Danish, Finnish, Romanian, Bulgarian, Czech, Slovak, Russian, Ukrainian, Turkish, Mandarin Chinese, Japanese, Korean, Malay, Hindi, Thai, Vietnamese, Indonesian, Catalan, Slovenian, Welsh, Greek [10]docs.synthflow.ai/about-supported-languages“English (you can choose between American, British and Australian accents), Brazilian Portuguese, European Portuguese, Spanish, French, German, Italian, Greek, Dutch, Polish, Swedish, Norwegian, Danish, Finnish, Romanian, Bulgarian, Czech, Slovak, Russian, Ukrainian, Turkish, Mandarin, Japanese, Korean, Malay, Hindi, Thai, Vietnamese, Indonesian, Catalan, Slovenian, Welsh”

Input types

PSTN phone call, SIP, WebSocket, inbound webhook, web widget

Output types

audio stream, call transcript, webhook events, call recording, structured call summary, analytics data, SMS

Webhooks

✓ Yes [11]docs.synthflow.ai/webhooks“Post-call webhooks - After a call ends with configured external_webhook_url in call requests; Inbound webhooks - Within ~10s of an inbound call starting configured via inbound_call_webhook_url on agents”

Sandbox / test mode

✗ No [12]docs.synthflow.ai/billing“No dedicated sandbox environment is explicitly mentioned. The Test Center for simulating calls operates within the live environment.”

SDK languages

Unknown

MCP server

✗ No [13]github.com/SynthFlowAI

SOC 2

Unknown [14]feedback.synthflow.ai/changelog/big-updates-soc-2-and-hipaa-compliance-azure-openai-service“SOC 2 Certification: Guaranteed industry-leading data security and privacy protection”synthflow.ai/blog/hipaa-compliant-ai-agents“Synthflow holds SOC 2, HIPAA, PCI DSS Level 1, ISO 27001, and GDPR certifications — SOC 2 type (I vs II) not specified on official pages”

HIPAA

✓ Yes [15]synthflow.ai/blog/hipaa-compliant-ai-agents“Synthflow holds SOC 2, HIPAA, PCI DSS Level 1, ISO 27001, and GDPR certifications”feedback.synthflow.ai/changelog/big-updates-soc-2-and-hipaa-compliance-azure-openai-service“HIPAA Certification: Safely manage sensitive patient data for healthcare and beyond”

GDPR

✓ Yes [16]synthflow.ai/blog/hipaa-compliant-ai-agents“Synthflow holds SOC 2, HIPAA, PCI DSS Level 1, ISO 27001, and GDPR certifications”synthflow.ai/industry/financial-services“Synthflow's infrastructure is certified across SOC 2, HIPAA, PCI DSS, and GDPR — with full encryption, audit logs, and region-based hosting built into every release.”

ISO 27001

✓ Yes [17]synthflow.ai/blog/hipaa-compliant-ai-agents“Synthflow holds SOC 2, HIPAA, PCI DSS Level 1, ISO 27001, and GDPR certifications”synthflow.ai/industry/financial-services“ISO 27001 Compliance Badge in the footer section under 'Trusted & Verified By'”

PCI DSS

✓ Yes [18]synthflow.ai/blog/hipaa-compliant-ai-agents“Synthflow holds SOC 2, HIPAA, PCI DSS Level 1, ISO 27001, and GDPR certifications”synthflow.ai/industry/financial-services“Synthflow's infrastructure is certified across SOC 2, HIPAA, PCI DSS, and GDPR”

Published SLA

✗ No [19]docs.synthflow.ai/pay-as-you-go“PAYG does not include SLA guarantees. The 99.99% SLA is available only with the Enterprise plan.”docs.synthflow.ai/billing“Enterprise — SLA: "99.99% uptime" — Support: Dedicated — Target use case: Teams handling 10,000+ minutes monthly”

Rate limits

Pay As You Go: 1 call attempt per second (CAPS); 5 concurrent calls included (expandable at $20/unit/month); 30 API requests/minute. Agency legacy accounts: up to 100 concurrent calls. [20]docs.synthflow.ai/cuncurrency-calling-limits“CAPS — Call Attempts Per Second: Pay As You Go: 1 call/second. Concurrency limit — Pay As You Go: 5 units (expandable at US$20/unit)”docs.synthflow.ai/pay-as-you-go“API rate limit: 30 requests/minute”

Known restrictions

No official SDK libraries; REST API only, BYO-LLM requires connecting your own OpenAI key; BYO-voice via ElevenLabs integration, PAYG concurrency capped at 5 simultaneous calls by default (expandable), CAPS limit of 1 call/second on PAYG; exceeding limits returns HTTP 429, White-label toolkit requires $2,000/month add-on, Legacy Pro/Growth/Agency subscription plans no longer available to new customers

• Docs
• llms.txt
• Status page

Docs rendering: static · llms.txt present

API style

rest

Base URL

https://api.synthflow.ai/v2

Version

v2

Versioning

url

Stability

ga

Auth methods

api_key

Idempotency keys

✗ No

Error format

vendor-specific

Webhook signing

hmac_sha256

Rate limit

1 / second

• Auth docs
• Quickstart
• Webhook events
• Deprecation policy

Launched

2023-01-01

GA

2024-01-01

Notable customers

Freshworks

• ElevenLabs Conversational AI (ElevenAgents)

  "Deploy human-like Conversational AI in minutes. ElevenLabs delivers low latency interactions in dozens of languages with enterprise-grade security."

  Hybrid · free tier · public pricing · self-serve

• OpenAI Realtime API (gpt-realtime)

  "The Realtime API enables low-latency, bidirectional audio communication for building voice agents and audio applications."

  Usage · public pricing · self-serve

• Telnyx Voice AI Agents

  "Carrier-grade Voice AI from Telnyx. Sub-200ms latency, 80+ languages, A-level STIR/SHAKEN attestation, and one platform that replaces 5 vendors."

  Usage · public pricing · self-serve

• Twilio ConversationRelay

  "Twilio's Conversation Relay empowers you to build powerful AI voice experiences for your customers. Let Twilio handle the heavy lifting of speech recognition, text-to-speech, and voice synthesis."

  Usage · public pricing · self-serve

• Vapi

  "Build and deploy voice agents that deliver the outcomes you want at the scale your customers need."

  Usage · free tier · public pricing · self-serve

• Cartesia Line

  "Turn any text agent into a world-class conversational agent, deployed anywhere."

  Hybrid · free tier · public pricing · self-serve

Synthflow AI alternatives · Synthflow AI vs ElevenLabs Conversational AI (ElevenAgents) · All Realtime Voice Agent APIs APIs

Each field above carries a numbered source - hover for a preview, click to jump here.

1. ↑Description: synthflow.ai
2. ↑Pricing model: docs.synthflow.ai · docs.synthflow.ai
3. ↑Published pricing: docs.synthflow.ai · docs.synthflow.ai
4. ↑Free tier: docs.synthflow.ai
5. ↑Self-serve signup: docs.synthflow.ai
6. ↑Requires sales call: docs.synthflow.ai
7. ↑Enterprise plan: synthflow.ai
8. ↑Supported actions: synthflow.ai · docs.synthflow.ai
9. ↑Regions: docs.synthflow.ai
10. ↑Languages: docs.synthflow.ai
11. ↑Webhooks: docs.synthflow.ai
12. ↑Sandbox: docs.synthflow.ai
13. ↑MCP server: github.com
14. ↑SOC 2: feedback.synthflow.ai · synthflow.ai
15. ↑HIPAA: synthflow.ai · feedback.synthflow.ai
16. ↑GDPR: synthflow.ai · synthflow.ai
17. ↑ISO 27001: synthflow.ai · synthflow.ai
18. ↑PCI DSS: synthflow.ai · synthflow.ai
19. ↑Published SLA: docs.synthflow.ai · docs.synthflow.ai
20. ↑Rate limits: docs.synthflow.ai · docs.synthflow.ai

Every field change, who made it, and when - from our audited data pipeline and editors.

1. 2026-06-21 Capabilities: {} → {"byo_models":true,"outbound_calling":true,"telephony_included":true}
2. 2026-06-21 Summary Md: (none) → Synthflow AI is a voice AI platform for automating inbound and outbound phone c…
3. 2026-06-21 Score Setup Speed: (none) → 45
4. 2026-06-21 Score Docs Quality: (none) → 25
5. 2026-06-21 Score Procurement Friction: (none) → 85
6. 2026-06-21 Score Trust Readiness: (none) → 55
7. 2026-06-21 Score Agent Friendliness: (none) → 45
8. 2026-06-21 Best For: (none) → Regulated or enterprise workloads - compliance attestations and an enterprise p…
9. 2026-06-21 Avoid If: (none) → You want to try it free before paying
10. 2026-06-21 Scoring Methodology: (none) → Scores are computed deterministically from this profile's published, sourced fi…
11. 2026-06-21 Score Pricing Transparency: (none) → 85
12. 2026-06-21 Llms Txt Present: (none) → Yes
13. 2026-06-21 Llms Txt URL: (none) → https://synthflow.ai/llms.txt
14. 2026-06-21 Rendering: (none) → static
15. 2026-06-21 Has Structured Data: (none) → Yes
16. 2026-06-21 Robots Allows Agents: (none) → Yes
17. 2026-06-21 Status Page URL: (none) → https://status.synthflow.ai
18. 2026-06-21 Docs URL: (none) → https://docs.synthflow.ai/getting-started
19. 2026-06-21 Has Published Pricing: set to Yes
20. 2026-06-21 Free Tier Available: set to No
21. 2026-06-21 Self Serve Signup: set to Yes
22. 2026-06-21 Requires Sales Call: set to No
23. 2026-06-21 Enterprise Plan Available: set to Yes
24. 2026-06-21 SOC 2: set to unknown
25. 2026-06-21 HIPAA: set to Yes
26. 2026-06-21 GDPR: set to Yes
27. 2026-06-21 ISO 27001: set to Yes
28. 2026-06-21 PCI DSS: set to Yes
29. 2026-06-21 SLA Published: set to No
30. 2026-06-21 SLA URL: set to https://synthflow.ai/pricing
31. 2026-06-21 Data Retention Policy URL: set to https://docs.synthflow.ai/privacy-policy
32. 2026-06-21 Documented Rate Limits: set to Pay As You Go: 1 call attempt per second (CAPS); 5 concurrent calls included (e…
33. 2026-06-21 Rate Limit Requests: set to 1
34. 2026-06-21 Rate Limit Window: set to second
35. 2026-06-21 Known Restrictions: set to No official SDK libraries; REST API only, BYO-LLM requires connecting your own …
36. 2026-06-21 Auth Methods: set to api_key
37. 2026-06-21 Auth Docs URL: set to https://docs.synthflow.ai/authentication
38. 2026-06-21 API Style: set to rest
39. 2026-06-21 Base URL: set to https://api.synthflow.ai/v2
40. 2026-06-21 API Version: set to v2
41. 2026-06-21 Versioning Scheme: set to url
42. 2026-06-21 Stability: set to ga
43. 2026-06-21 Deprecation Policy URL: set to https://feedback.synthflow.ai/changelog
44. 2026-06-21 Quickstart URL: set to https://docs.synthflow.ai/getting-started-with-your-api
45. 2026-06-21 Idempotency Supported: set to No
46. 2026-06-21 Error Format: set to vendor-specific
47. 2026-06-21 Webhook Signing: set to hmac_sha256
48. 2026-06-21 Webhook Events URL: set to https://docs.synthflow.ai/reference/webhook
49. 2026-06-21 Requires Verification: set to No
50. 2026-06-21 Starting Price Usd: set to 0.09

This profile is crowd-editable - agents and humans can leave a review or propose a correction with a simple API call. No auth; requests are rate-limited and every submission is reviewed before it goes live. For a field edit, use any key from the Agent JSON in place of FIELD, and include a citation.

curl -X POST https://apio.sh/api/feedback/synthflow \
  -H 'Content-Type: application/json' \
  -d '{"kind":"review","rating":5,"body":"Your experience with this API…"}'

curl -X POST https://apio.sh/api/suggest/synthflow/FIELD \
  -H 'Content-Type: application/json' \
  -d '{"value":"corrected value","citations":[{"url":"https://source.example/page","excerpt":"supporting quote"}],"note":"what changed and why"}'

All the ways to contribute →